Method of automatically controlling motorized window treatments

ABSTRACT

A load control system automatically controls the amount of daylight entering a building through at least one window of a non-linear façade of the building. The load control system comprises at least two motorized window treatments located along the non-linear façade, and a system controller. The controller is configured to calculate an optimal position for the motorized window treatments at each of a plurality of different times during a subsequent time interval using at least two distinct façade angles of the non-linear façade, such that a sunlight penetration distance will not exceed a maximum distance during the time interval. The controller is configured to use the optimal positions to determine a controlled position to which both of the motorized window treatments will be controlled during the time interval and to automatically adjust each of the motorized window treatments to the controlled position at the beginning of the time interval.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional applicationSer. No. 14/578,105, filed Dec. 19, 2014, which is a non-provisionalapplication of commonly-assigned U.S. Provisional Application No.61/919,874, filed Dec. 23, 2013, entitled METHOD OF AUTOMATICALLYCONTROLLING MOTORIZED WINDOW TREATMENTS, the entire disclosures of whichare hereby incorporated by reference.

BACKGROUND

Field of the Disclosure

The present disclosure relates to a load control system for controllinga plurality of electrical loads and a plurality of motorized windowtreatments in a space, and more particularly, to a procedure forautomatically controlling one or more motorized window treatments toprevent direct sun glare on work spaces in the space while minimizingoccupant distractions.

Description of the Related Art

Motorized window treatments, such as, for example, motorized rollershades and draperies, provide for control of the amount of sunlightentering a space. Some prior art motorized window treatments have beenautomatically controlled in response to various inputs, such as daylightsensors and timeclocks. However, the automatic control algorithms ofprior art motorized window treatments have resulted in frequent movementof the motorized window treatments, thus causing many distractions tooccupants of the space.

Some prior art load control systems have automatically controlled one ormore motorized window treatments to prevent sun glare while minimizingoccupant distractions. For example, such a load control system mayoperate to limit the sunlight penetration distance in a space of abuilding. A system controller (e.g., a central controller) of the loadcontrol system may be configured to generate a timeclock schedule forcontrolling the motorized window treatments for limiting the sunlightpenetration distance to a maximum penetration distance. The systemcontroller may comprise an astronomical timeclock and may be configuredto control the motorized window treatments according to the timeclockschedule to limit the sunlight penetration distance in the space.

Prior to execution of the timeclock schedule (e.g., at or before thebeginning of each day), the system controller may be configured toanalyze the position of the sun throughout the coming day on each façadeof the building to determine the positions to which the motorized windowtreatments along a single façade must be controlled in order to preventthe sunlight penetration distance from exceeding the maximum penetrationdistance. The system controller may be configured to build the timeclockschedule to have a number of events throughout the day, such that thenumber of movements during each day does not exceed a maximum number ofmovements to minimize occupant distractions. The system controller maybe configured to determine the positions to which to control themotorized window treatments on each façade at the event times of thetimeclock procedure using the determined positions to which to controlthe motorized window treatments to prevent the sunlight penetrationdistance from exceeding the maximum penetration distance. Examples ofload control systems for controlling motorized window treatments tolimit the sunlight penetration distance in a space while minimizingoccupant distractions are described in greater detail incommonly-assigned U.S. Pat. No. 8,288,981, issued Oct. 16, 2012,entitled METHOD OF AUTOMATICALLY CONTROLLING A MOTORIZED WINDOWTREATMENT WHILE MINIMIZING OCCUPANT DISTRACTIONS, the entire disclosureof which is hereby incorporated by reference.

Since the penetration distance in a space is dependent upon the positionof the sun as well as an angle of the façade with respect to true north,all of the motorized window treatments along a single façade willtypically be controlled to the same position by the system controllerwhen executing the timeclock schedule. However, the motorized windowtreatments on adjacent facades that have different façade angles may becontrolled to different positions. If the perimeter of a building ischaracterized by a number of façade angles, the motorized windowtreatments along the perimeter of the building may each be controlled todifferent positions, which may detract from the aesthetic appearance ofthe motorized window treatments in the building. In addition, somebuilding have continuously curved facades, where the motorized windowtreatments located along the façade are each arranged at differentangles. Accordingly, there is a need for a method of automaticallycontrolling one or more motorized window treatments along a non-linearfaçade to prevent sun glare, while minimizing occupant distractions andmaintaining alignment of adjacent motorized window treatments along thefaçade.

SUMMARY

As described herein, a load control system may automatically control theamount of daylight entering a space of a building through at least onewindow of a non-linear façade of the building, where the non-linearfaçade is characterized by at least two distinct façade angles. The loadcontrol system may comprise at least two motorized window treatmentslocated along the non-linear façade for controlling the amount ofdaylight entering the space, and a system controller configured totransmit digital commands to the motorized window treatments forcontrolling the motorized window treatments. The controller may beconfigured to calculate an optimal position for the motorized windowtreatments at each of a plurality of different times during a subsequenttime interval using the at least two distinct façade angles. The optimalposition may be calculated such that a sunlight penetration distance maynot exceed a desired maximum sunlight penetration distance at each ofthe plurality of different times during the time interval. Thecontroller may be configured to use the optimal positions at theplurality of different times during the time interval to determine acontrolled position to which both of the motorized window treatmentswill be controlled during the time interval. The controller may beconfigured to automatically adjust the position of each of the motorizedwindow treatments to the controlled position at the beginning of thetime interval so as to prevent the sunlight penetration distance fromexceeding the desired maximum sunlight penetration distance during thetime interval.

For example, the system controller may be configured to determine arepresentative façade angle at each of the plurality of different timesduring the time interval using the at least two distinct façade angles,and calculate the optimal position for the motorized window treatmentsat each of the plurality of different times during the time intervalusing the representative façade angle. The representative façade anglemay be equal to a calculated solar azimuth angle of the sun at aspecific time if the solar azimuth angle is between the at least twofaçade angles. In addition, the system controller may be configured tocalculate optimal positions for each of first and second motorizedwindow treatments that are arranged at respective first and secondfaçade angles, and to set the controlled positions of the timeclockschedule equal to the lowest of the optimal positions for the first andsecond motorized window treatments at the plurality of different timesduring the time interval. Further, the system controller may beconfigured to calculate an optimal position for each of a plurality ofmotorized window treatments at a respective façade angle at each of theplurality of different times during the time interval, and to set thecontrolled position of the timeclock schedule equal to the lowestposition of the optimal positions of at the plurality of different timesduring the time interval.

In addition, a method of automatically controlling at least twomotorized window treatments located along a non-linear façade of abuilding is also described herein. The non-linear façade may becharacterized by at least two distinct façade angles. The method maycomprise the steps of: (1) calculating an optimal position for themotorized window treatments at each of a plurality of different timesduring a subsequent time interval using the at least two distinct façadeangles, the optimal position calculated such that a sunlight penetrationdistance will not exceed a desired maximum sunlight penetration distanceat each of the plurality of different times during the time interval;(2) using the optimal positions that were calculated at the plurality ofdifferent times during the time interval to determine a controlledposition to which both of the motorized window treatments will becontrolled during the time interval; and (3) automatically adjusting theposition of each of the motorized window treatments to the controlledposition at the beginning of the time interval so as to prevent thesunlight penetration distance from exceeding the desired maximumsunlight penetration distance during the time interval.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of an example load control system.

FIG. 2 is a simplified side view of an example of a space of a buildinghaving a window covered by a motorized roller shade of a load controlsystem.

FIG. 3A is a side view of the window of FIG. 2 illustrating a sunlightpenetration depth.

FIG. 3B is a top view of the window of FIG. 2 when the sun is directlyincident upon the window.

FIG. 3C is a top view of the window of FIG. 2 when the sun is notdirectly incident upon the window.

FIG. 4 is a simplified flowchart of an example timeclock configurationprocedure executed periodically by a system controller of a load controlsystem.

FIG. 5 is a simplified flowchart of an example optimal shade positionprocedure executed during the timeclock configuration procedure of FIG.4.

FIGS. 6A-6C show example plots of optimal shade positions of motorizedroller shades on different facades of the building during different daysof the year as generated by the optimal shade position procedure of FIG.5.

FIG. 7 is a simplified flowchart of an example timeclock event creationprocedure executed during the timeclock configuration procedure of FIG.4.

FIGS. 8A-8C show example plots of controlled shade positions ofmotorized roller shades on different facades of the building duringdifferent days of the year as generated by the timeclock event creationprocedure of FIG. 7.

FIG. 9 is a simplified flowchart of a timeclock schedule executionprocedure executed by a system controller of a load control system.

FIG. 10 is a simplified flowchart of another example timeclockconfiguration procedure executed periodically by a system controller ofload control system of FIG. 1.

FIGS. 11A-11C are simplified flowcharts of a timeclock event creationprocedure executed during the timeclock configuration procedure of FIG.10.

FIG. 12 is a simplified flowchart of the timeclock event optimizationprocedure executed during the timeclock configuration procedure of FIG.10.

FIGS. 13A-13C show example plots of controlled shade positions of themotorized roller shades on different facades of the building duringdifferent days of the year as generated by the timeclock event creationprocedure of FIGS. 11A-11C and the timeclock event optimizationprocedure of FIG. 12.

FIG. 14 is a simplified top view of an example of a load control systeminstalled in a space (e.g., of a building having a non-linear façade).

FIG. 15 is a simplified flowchart of an example timeclock configurationprocedure executed periodically by a system controller (e.g., a shadecontroller) of a load control system.

FIGS. 16-18 show simplified flowcharts of example optimal shade positionprocedures that may be executed periodically by a system controller(e.g., a shade controller) of a load control system.

FIG. 19 is a simplified flowchart of an example representative façadeangle determination procedure executed by a system controller (e.g., ashade controller) of a load control system.

DETAILED DESCRIPTION

FIG. 1 is a simple diagram of an example load control system forcontrolling the amount of power delivered from an alternating-current(AC) power source (not shown) to one or more electrical loads. The loadcontrol system 100 may comprise a system controller 110 (e.g., a loadcontroller or a central controller) operable to transmit and receivedigital messages via wired and/or wireless communication links. Forexample, the system controller 110 may be coupled to one or more wiredcontrol devices via a wired digital communication link 104. In addition,the system controller 110 may be configured to transmit and/or receivewireless signals, e.g., radio-frequency (RF) signals 106, to communicatewith one or more wireless control devices. The load control system 100may comprise a number of control-source devices (e.g., input devicesoperable to transmit digital messages in response to user inputs,occupancy/vacancy conditions, changes in measured light intensity, etc.)and a number of control-target devices (e.g., load control devicesoperable to receive digital messages and control respective electricalloads in response to the received digital messages). A single controldevice of the load control system 100 may operate as both acontrol-source and a control-target device. The system controller 110may be configured to receive digital messages from the control-sourcedevices and transmit digital messages to the control-target devices inresponse to the digital messages received from the control-sourcedevices.

The load control system 100 may comprise a load control device, such asa dimmer switch 120, for controlling a lighting load 122. The dimmerswitch 120 may be adapted to be wall-mounted in a standard electricalwallbox. Alternatively, the dimmer switch 120 may comprise a tabletop orplug-in load control device. The dimmer switch 120 may comprise a toggleactuator 124 (e.g., a button) and/or an intensity adjustment actuator126 (e.g., a rocker switch). Successive actuations of the toggleactuator 124 may toggle, e.g., turn off and on, the lighting load 122.Actuations of an upper portion or a lower portion of the intensityadjustment actuator 126 may respectively increase or decrease the amountof power delivered to the lighting load 122 and thus increase ordecrease the intensity of the lighting load from a minimum intensity(e.g., approximately 1%) to a maximum intensity (e.g., approximately100%). The dimmer switch 120 may further comprise a plurality of visualindicators 128, e.g., light-emitting diodes (LEDs), which may bearranged in a linear array and may be illuminated to provide feedback ofthe intensity of the lighting load 122. The dimmer switch 120 may beconfigured to receive digital messages from the system controller 110via the RF signals 106 and to control the lighting load 122 in responseto the received digital messages. The dimmer switch 120 may also beconfigured to receive digital messages from the system controller 110via the digital communication link 104, when the dimmer switch iscoupled to the digital communication link 104.

The load control system 100 may further comprise one or moreremotely-located load control devices, such as light-emitting diode(LED) drivers 130 for driving respective LED light sources 132 (e.g.,LED light engines). The LED drivers 130 may be located remotely, forexample, in the lighting fixtures of the respective LED light sources132. The LED drivers 130 may be configured to receive digital messagesfrom the system controller 110 via the digital communication link 104and to control the respective LED light sources 132 in response to thereceived digital messages. Alternatively, the LED drivers 130 could becoupled to a separate digital communication link, such as an Ecosystem®or digital addressable lighting interface (DALI) communication link, andthe load control system 100 could further comprise a digital lightingcontroller coupled between the digital communication link 104 and theseparate communication link. In addition, the LED drivers 132 couldalternatively comprise internal RF communication circuits or be coupledto external RF communication circuits (e.g., mounted external to thelighting fixtures, such as to a ceiling) for transmitting and/orreceiving the RF signals 106. The load control system 100 may furthercomprise other types of remotely-located load control devices, such as,for example, electronic dimming ballasts for driving fluorescent lamps.

The load control system 100 may further comprise a plurality of daylightcontrol devices, e.g., motorized window treatments, such as motorizedroller shades 140, to control the amount of daylight entering thebuilding in which the load control system is installed. Each motorizedroller shade 140 may comprise a covering material (e.g., a shade fabric)that is wound around a roller tube for raising and lowering the shadefabric. Each motorized roller shade 140 also comprises an electronicdrive unit (EDU) 142, which may be located inside the roller tube of themotorized roller shade. The electronic drive units 142 may be coupled tothe digital communication link 104 for transmitting and/or receivingdigital messages, and may be configured to adjust the position of awindow treatment fabric in response to digital messages received fromthe system controller 110 via the digital communication link 104.Alternatively, each electronic drive unit 142 could comprise an internalRF communication circuit or be coupled to an external RF communicationcircuit (e.g., located outside of the roller tube) for transmittingand/or receiving the RF signals 106. In addition, the load controlsystem 100 could comprise other types of daylight control devices, suchas, for example, a cellular shade, a drapery, a Roman shade, a Venetianblind, a Persian blind, a pleated blind, a tensioned roller shadesystems, an electrochromic or smart window, or other suitable daylightcontrol device.

The load control system 100 may comprise one or more other types of loadcontrol devices, such as, for example, a screw-in luminaire including adimmer circuit and an incandescent or halogen lamp; a screw-in luminaireincluding a ballast and a compact fluorescent lamp; a screw-in luminaireincluding an LED driver and an LED light source; an electronic switch,controllable circuit breaker, or other switching device for turning anappliance on and off; a plug-in load control device, controllableelectrical receptacle, or controllable power strip for controlling oneor more plug-in loads; a motor control unit for controlling a motorload, such as a ceiling fan or an exhaust fan; a drive unit forcontrolling a motorized window treatment or a projection screen;motorized interior or exterior shutters; a thermostat for a heatingand/or cooling system; a temperature control device for controlling asetpoint temperature of an HVAC system; an air conditioner; acompressor; an electric baseboard heater controller; a controllabledamper; a variable air volume controller; a fresh air intake controller;a ventilation controller; hydraulic valves for use in radiators andradiant heating system; a humidity control unit; a humidifier; adehumidifier; a water heater; a boiler controller; a pool pump; arefrigerator; a freezer; a television or computer monitor; a videocamera; an audio system or amplifier; an elevator; a power supply; agenerator; an electric charger, such as an electric vehicle charger; andan alternative energy controller.

The load control system 100 may comprise one or more input devices,e.g., such as a wired keypad device 150, a battery-powered remotecontrol device 152, an occupancy sensor 154, and a daylight sensor 156.In addition, the load control system 100 may comprise one or more windowsensors 158 (e.g., cloudy-day or shadow sensors). The wired keypaddevice 150 may be configured to transmit digital messages to the systemcontroller 110 via the digital communication link 104 in response to anactuation of one or more buttons of the wired keypad device 150. Thebattery-powered remote control device 152, the occupancy sensor 154, thedaylight sensor 156, and/or the window sensor 158 may be wirelesscontrol devices (e.g., RF transmitters) configured to transmit digitalmessages to the system controller 110 via the RF signals 106 (e.g.,directly to the system controller). For example, the battery-poweredremote control device 152 may be configured to transmit digital messagesto the system controller 110 via the RF signals 106 in response to anactuation of one or more buttons of the battery-powered remote controldevice. The system controller 110 may be configured to transmit one ormore digital messages to the load control devices (e.g., the dimmerswitch 120, the LED drivers 130, and/or the motorized roller shades 140)in response to the digital messages received from the wired keypaddevice 150, the battery-powered remote control device 152, the occupancysensor 154, the daylight sensor 156, and/or the window sensor 158.

The load control system 100 may further comprise a wireless adapterdevice 159 coupled to the digital communication link 104 and configuredto receive the RF signals 106. The wireless adapter device 159 may beconfigured to transmit a digital message to the system controller 110via the digital communication link 104 in response to a digital messagereceived from one of the wireless control devices via the RF signals106. For example, the wireless adapter device 159 may simply re-transmitthe digital messages received from the wireless control devices on thedigital communication link 104.

The occupancy sensor 154 may be configured to detect occupancy and/orvacancy conditions in the space in which the load control system 100 isinstalled. The occupancy sensor 154 may transmit digital messages to thesystem controller 110 via the RF signals 106 in response to detectingthe occupancy or vacancy conditions. The system controller 110 may eachbe configured to turn one or more of the lighting load 122 and the LEDlight sources 132 on and off in response to receiving an occupiedcommand and a vacant command, respectively. Alternatively, the occupancysensor 154 may operate as a vacancy sensor, such that the lighting loadsare turned off in response to detecting a vacancy condition, but notturned on in response to detecting an occupancy condition. Examples ofRF load control systems having occupancy and vacancy sensors aredescribed in greater detail in commonly-assigned U.S. Pat. No.8,009,042, issued Aug. 30, 2011, entitled RADIO-FREQUENCY LIGHTINGCONTROL SYSTEM WITH OCCUPANCY SENSING; U.S. Pat. No. 8,199,010, issuedJun. 12, 2012, entitled METHOD AND APPARATUS FOR CONFIGURING A WIRELESSSENSOR; and U.S. Pat. No. 8,228,184, issued Jul. 24, 2012, entitledBATTERY-POWERED OCCUPANCY SENSOR, the entire disclosures of which arehereby incorporated by reference.

The daylight sensor 156 may be configured to measure a total lightintensity in the space in which the load control system is installed.The daylight sensor 156 may transmit digital messages including themeasured light intensity to the system controller 110 via the RF signals106 for controlling the intensities of one or more of the lighting load122 and the LED light sources 132 in response to the measured lightintensity. Examples of RF load control systems having daylight sensorsare described in greater detail in commonly-assigned U.S. Pat. No.8,410,706, issued Apr. 2, 2013, entitled METHOD OF CALIBRATING ADAYLIGHT SENSOR; and U.S. Pat. No. 8,451,116, issued May 28, 2013,entitled WIRELESS BATTERY-POWERED DAYLIGHT SENSOR, the entiredisclosures of which are hereby incorporated by reference.

In addition, the load control system 100 may comprise other types ofinput devices, such as, for example, temperature sensors; humiditysensors; radiometers; pressure sensors; smoke detectors; carbon monoxidedetectors; air-quality sensors; motion sensors; security sensors;proximity sensors; fixture sensors; partition sensors; keypads; kineticor solar-powered remote controls; key fobs; cell phones; smart phones;tablets; personal digital assistants; personal computers; laptops;timeclocks; audio-visual controls; safety devices; power monitoringdevices (such as power meters, energy meters, utility submeters, utilityrate meters, etc.); central control transmitters; residential,commercial, or industrial controllers; or any combination of these inputdevices.

The system controller 110 may be configured to control the load controldevices (e.g., the dimmer switch 120, the LED drivers 130, and/or themotorized roller shades 140) according to a timeclock schedule, whichmay be stored in a memory in the system controller. The timeclockschedule may include a number of timeclock events, each having an eventtime and a corresponding command or preset. The system controller 110may be configured to keep track of the present time and day and totransmit the appropriate command or preset at the respective event timeof each timeclock event.

The system controller 110 may be coupled to a network, such as awireless or wired local area network (LAN) via a network communicationbus 160 (e.g., an Ethernet communication link), e.g., for access to theInternet. The system controller 110 may be connected to a router 162 (orEthernet switch) via the network communication bus 160 for allowing thesystem controller 110 to communicate with additional system controllersfor controlling additional electrical loads. Alternatively, the systemcontroller 110 may be wirelessly connected to the network, e.g., usingWi-Fi technology. The system controller 110 may also be configured tocommunicate via the network with one or more network devices, such as, asmart phone (for example, an iPhone® smart phone, an Android® smartphone, or a Blackberry® smart phone), a personal computer 164, a laptop,a tablet device (for example, an iPad® hand-held computing device), aWi-Fi or wireless-communication-capable television, or any othersuitable Internet-Protocol-enabled device. The network device may beoperable to transmit digital messages to the system controller 110 inone or more Internet Protocol packets. Examples of load control systemsoperable to communicate with network devices on a network are describedin greater detail in commonly-assigned U.S. Patent ApplicationPublication No. 2013/0030589, published Jan. 31, 2013, entitled LOADCONTROL DEVICE HAVING INTERNET CONNECTIVITY, the entire disclosure ofwhich is hereby incorporated by reference.

The operation of the load control system 100 may be programmed andconfigured using the network device (e.g., the personal computer 164).The network device may execute a graphical user interface (GUI)configuration software for allowing a user to program how the loadcontrol system 100 will operate. The configuration software may generatea load control database that defines the operation and/or performance ofthe load control system 100. For example, the load control database mayinclude information regarding the different load control devices of theload control system (e.g., the dimmer switch 120, the LED drivers 130,and/or the motorized roller shades 140). The load control database mayalso include information regarding associations between the load controldevices and the input devices (e.g., the wired keypad device 150, thebattery-powered remote control device 152, the occupancy sensor 154, thedaylight sensor 156, and/or the window sensor 158), and how the loadcontrol devices respond to inputs received from the input devices.Examples of configuration procedures for load control systems aredescribed in greater detail in commonly-assigned U.S. Pat. No.7,391,297, issued Jun. 24, 2008, entitled HANDHELD PROGRAMMER FOR ALIGHTING CONTROL SYSTEM; U.S. Patent Application Publication No.2008/0092075, published Apr. 17, 2008, entitled METHOD OF BUILDING ADATABASE OF A LIGHTING CONTROL SYSTEM; and U.S. Patent ApplicationPublication No. 2014/0265568, published Sep. 18, 2014, entitledCOMMISSIONING LOAD CONTROL SYSTEMS, the entire disclosures of which arehereby incorporated by reference.

The system controller 110 may be configured to automatically control themotorized window treatments (e.g., the motorized roller shades 140) tosave energy and/or improve the comfort of the occupants of the buildingin which the load control system 100 is installed. For example, thesystem controller 110 may be configured to automatically control themotorized roller shades 140 in response to the timeclock schedule and/orthe daylight sensor 156 or the window sensor 158.

The load control system 100 may operate in a sunlight penetrationlimiting mode to control the amount of sunlight entering a space 170(FIG. 2) of a building to control a sunlight penetration distanced_(PEN) in the space 170. Specifically, the system controller 110 may beoperable to transmit digital messages to the motorized roller shades 140to limit the sunlight penetration distance d_(PEN) in the space 170 to adesired maximum sunlight penetration distance d_(MAX). The systemcontroller 100 may comprise an astronomical timeclock, such that thesystem controller is able to determine the sunrise time t_(SUNRISE) andthe sunset time t_(SUNSET) for each day of the year for a specificlocation. The system controller 110 may transmit commands to theelectronic drive units 142 to automatically control the motorized rollershades 140 in response to a timeclock schedule. Alternatively, thenetwork device (e.g., the personal computer 164) could comprise theastronomical timeclock and could transmit the digital messages to themotorized roller shades 140 to control the sunlight penetration distanced_(PEN) in the space 170.

The one or more window sensors 158 may be mounted to the inside surfacesof one or more windows 176 (FIG. 2) in the space 170 or to the exteriorof the building. Each window sensor 158 may be battery-powered and maybe operable to transmit the RF signals 106 to the wireless adapterdevice 159. The wireless adapter device 159 may be operable to transmitdigital messages to the system controller 110 via the digitalcommunication link 104 in response to the RF signals 106 from the windowsensors 158. The window sensors 158 are each configured to measure thelight intensity at the sensor, and to transmit a digital messageincluding the measured light intensity, for example, when the magnitudeof the light intensity changes by a predetermined amount (e.g.,approximately 20%). In response to the digital messages received fromthe window sensors 158, via the wireless adapter device 159 for example,the system controller 110 may be configured to enable and/or disable thesunlight penetration limiting mode as will be described in greaterdetail below. The window sensors 158 may be located at different windowsaround the building (as well as a plurality of sensor receiver modules),such that the load control system 100 may enable the sunlightpenetration limiting mode in some areas of the building and not inothers. Examples of window sensors are described in greater detail incommonly assigned U.S. Patent Application Publication No. 2014/0156079,published Jun. 5, 2014, entitled METHOD OF CONTROLLING A MOTORIZEDWINDOW TREATMENT, the entire disclosure of which is hereby incorporatedby reference.

In addition, the load controls system 100 could comprise pairs of windowsensors. The pairs of window sensors may be located on opposite sides ofa mullion of a window of the building or at opposite sides of a window.Each one of the two sensors of the paired window sensors may looksimilar to the daylight sensor 156 shown in FIG. 1, and may have a lensthat is directed outside the window. The system controller 110 may beresponsive to the measured light intensities of both of the sensors ofeach pair of sensors as if the pair of sensors was a single windowsensor 158. For example, the system controller 110 may add the measuredlight intensities of both of the sensors of each pair of sensors and mayenable and disable the sunlight penetration limiting mode in response tothe sum of the measured light intensities of both of the sensors of eachpair of sensors.

FIG. 2 is a simplified side view of an example of the space 170illustrating the sunlight penetration distance d_(PEN), which iscontrolled by the motorized roller shades 140. As shown in FIG. 2, thebuilding comprises a façade 174 (e.g., one side of a four-sidedrectangular building) having a window 176 for allowing sunlight to enterthe space. The space 170 also comprises a work surface, e.g., a table178, which has a height h_(WORK). The window sensor 158 may be mountedto the inside surface of the window 176 as shown in FIG. 2. Themotorized roller shade 140 is mounted above the window 176 and comprisesa roller tube 182 around which a shade fabric 180 is wrapped. The shadefabric 180 may have a hembar 184 at the lower edge of the shade fabric.The electronic drive unit 142 may rotate the roller tube 182 to move theshade fabric 180 between a fully-open position P_(FO) (e.g., in whichthe window 176 is not covered) and a fully-closed position P_(FC) (e.g.,in which the window 176 is fully covered). Further, the electronic driveunit 142 may control the position of the shade fabric 180 to one of aplurality of preset positions between the fully-open position Pro andthe fully-closed position P_(FC).

The sunlight penetration distance d_(PEN) is the distance from thewindow 176 and/or the façade 174 at which direct sunlight shines intothe room. The sunlight penetration distance d_(PEN) is a function of aheight h_(WIN) of the window 176 and an angle φ_(F) of the façade 174with respect to true north (e.g., a façade angle of zero degrees), aswell as a solar elevation angle θ_(S) and a solar azimuth angle φ_(S),which define the position of the sun in the sky. The solar elevationangle θ_(S) and the solar azimuth angle φ_(S) are functions of thepresent date and time, as well as the position (e.g., the longitude andlatitude) of the building in which the space 170 is located. The solarelevation angle θ_(S) may be the angle between a line directed towardsthe sun and a line directed towards the horizon at the position of thebuilding. The solar elevation angle θ_(S) can also be thought of as theangle of incidence of the sun's rays on a horizontal surface. The solarazimuth angle φ_(S) is the angle formed by the line from the observer totrue north and the line from the observer to the sun projected on theground. When the solar elevation angle θ_(S) is small (e.g., aroundsunrise and sunset), small changes in the position of the sun may resultin relatively large changes in the magnitude of the sunlight penetrationdi stance d_(PEN).

The sunlight penetration distance d_(PEN) of direct sunlight onto thetable 178 of the space 170 (which may be measured normal to the surfaceof the window 176) can be determined by considering a triangle formed bythe length

of the deepest penetrating ray of light (which is parallel to the pathof the ray), the difference between the height h_(WIN) of the window 176and the height h_(WORK) of the table 178, and the distance between thetable and the wall of the façade 174 e.g., the sunlight penetrationdistance d_(PEN)) as shown in the side view of the window 176 in FIG.3A, e.g.,

tan(θ_(S))=(h _(WIN) −h _(WORK))/

,  (Equation 1)

where θ_(S) is the solar elevation angle of the sun at a given date andtime for a given location (e.g., longitude and latitude) of thebuilding.

If the sun is directly incident upon the window 176, a solar azimuthangle φ_(S) and the façade angle φ_(F) (e.g., with respect to truenorth) are equal as shown by the top view of the window 176 in FIG. 3B.Accordingly, the sunlight penetration distance d_(PEN) may equal thelength

of the deepest penetrating ray of light. However, if the façade angleφ_(F) is not equal to the solar azimuth angle φ_(S), the sunlightpenetration distance d_(PEN) is a function of the cosine of thedifference between the façade angle φ_(F) and the solar azimuth angleφ_(S), e.g.,

d _(PEN) =l·cos(φ_(F)−φ_(S)|),  (Equation 2)

as shown by the top view of the window 176 in FIG. 3C.

As previously mentioned, the solar elevation angle θ_(S) and the solarazimuth angle φ_(S) define the position of the sun in the sky and arefunctions of the position (e.g., the longitude and latitude) of thebuilding in which the space 170 is located and the present date andtime. The following equations may be used to approximate the solarelevation angle θ_(S) and the solar azimuth angle φ_(S). The equation oftime defines essentially the difference in a time as given by a sundialand a time as given by a clock. This difference is due to the obliquityof the Earth's axis of rotation. The equation of time can beapproximated by

E=9.87·sin(2B)−7.53·cos(B)−1.5 sin(B),  (Equation 3)

where B=[360°·(N_(DAY)−81)]/364, and N_(DAY) is the present day-numberfor the year (e.g., N_(DAY) equals one for January 1, N_(DAY) equals twofor January 2, and so on).

The solar declination δ is the angle of incidence of the rays of the sunon the equatorial plane of the Earth. If the eccentricity of Earth'sorbit around the sun is ignored and the orbit is assumed to be circular,the solar declination is given by:

δ=23.45°·sin [360°/365·(N _(DAY)+284)].  (Equation 4)

The solar hour angle H is the angle between the meridian plane and theplane formed by the Earth's axis and current location of the sun, e.g.,

H(t)={¼[t+E(4·λ)+(60·t _(TZ))]}−180°,  (Equation 5)

where t is the present local time of the day, λ, is the local longitude,and t_(TZ) is the time zone difference (e.g., in unit of hours) betweenthe local time t and Greenwich Mean Time (GMT). For example, the timezone difference t_(TZ) for the Eastern Standard Time (EST) zone is −5.The time zone difference t_(TZ) can be determined from the locallongitude λ and latitude φ of the building. For a given solar hour angleH, the local time can be determined by solving Equation 5 for the timet, e.g.,

t=720+4·(H+λ)−(60·t _(TZ))−E.  (Equation 6)

When the solar hour angle H equals zero, the sun is at the highest pointin the sky, which is referred to as “solar noon” time t_(SN), e.g.,

t _(SN)=720+(4·λ)−(60·t _(TZ))−E.  (Equation 7)

A negative solar hour angle H indicates that the sun is east of themeridian plane (e.g., morning), while a positive solar hour angle Hindicates that the sun is west of the meridian plane (e.g., afternoon orevening).

The solar elevation angle θ_(S) as a function of the present local timet can be calculated using the equation:

θ_(S)(t)=sin⁻¹[cos(H(t))·cos(δ)·cos(φ)+sin(δ)·sin(φ)],  (Equation 8)

wherein φ is the local latitude. The solar azimuth angle φ_(S) as afunction of the present local time t can be calculated using theequation:

φ_(S)(t)=180°·C(t)·cos⁻¹ [X(t)/cos(θ_(S)(t))],  (Equation 9)

where

X(t)=[cos(H(t))·cos(δ)·sin(φ)−sin(δ)·cos(φ)],  (Equation 10)

and C(t) equals negative one if the present local time t is less than orequal to the solar noon time t_(SN) or one if the present local time tis greater than the solar noon time t_(SN). The solar azimuth angleφ_(S) can also be expressed in terms independent of the solar elevationangle θ_(S), e.g.,

φ_(S)(t)=tan⁻¹[−sin(H(t))·cos(δ)/Y(t)],  (Equation 11)

where

Y(t)=[sin(δ)·cos(φ)−cos(δ)·sin(φ)·cos(H(t))].  (Equation 12)

Thus, the solar elevation angle θ_(S) and the solar azimuth angle φ_(S)are functions of the local longitude λ, and latitude φ and the presentlocal time t and date (e.g., the present day-number N_(DAY)). UsingEquations 1 and 2, the sunlight penetration distance can be expressed interms of the height h_(WIN) of the window 176, the height h_(WORK) ofthe table 178, the solar elevation angle θ_(S), and the solar azimuthangle φ_(S).

As previously mentioned, the system controller 110 may operate in thesunlight penetration limiting mode to control the motorized rollershades 140 to limit the sunlight penetration distance d_(PEN) to be lessthan the desired maximum sunlight penetration distance d_(MAX). Forexample, the sunlight penetration distance d_(PEN) may be limited suchthat the sunlight does not shine directly on the table 178 to preventsun glare on the table. The desired maximum sunlight penetrationdistance d_(MAX) may be entered using the GUI software of the networkdevice (e.g., the personal computer 164) and may be stored in memory inthe system controller 110. In addition, the user may also use the GUIsoftware of the network device to enter the present date and time, thepresent time zone, the local longitude λ and latitude φ of the building,the façade angle φ_(F) for each façade 174 of the building, the heighth_(WIN) of the windows 176 in spaces 170 of the building, and theheights h_(WORK) of the workspaces (e.g., tables 178) in the spaces ofthe building. These operational characteristics (or a subset of theseoperational characteristics) may also be stored in the memory of thesystem controller 110. Further, the motorized roller shades 140 may becontrolled such that distractions to an occupant of the space 170 (e.g.,due to movements of the motorized roller shades 140) are minimized.

The system controllers 110 of the load control system 110 may beoperable to generate a timeclock schedule defining the desired operationof the motorized roller shades 140 for each of the façades 174 of thebuilding to limit the sunlight penetration distance d_(PEN) in the space170. For example, the system controller 110 may generate once each dayat midnight a subsequent timeclock schedule for limiting the sunlightpenetration distance d_(PEN) in the space 170 for the next day. Thesystem controller 110 may be operable to calculate optimal shadepositions of the motorized roller shades 140 in response to the desiredmaximum sunlight penetration distance d_(MAX) at a plurality of timesfor the next day. The system controllers 110 are then operable to usethe calculated optimal shade positions as well as a user-selectedminimum time period T_(MIN) between shade movements and/or a minimumnumber N_(MIN) of shade movements per day to generate the timeclockschedule for the next day.

The minimum time period T_(MIN) that may exist between any twoconsecutive movements of the motorized roller shades and/or the minimumnumber N_(MIN) of shade movements per day may be entered using the GUIsoftware of the network device and may be stored in the memory in thesystem controllers 110. The user may select different values for desiredmaximum sunlight penetration distance d_(MAX), the minimum time periodT_(MIN) that may exist between any two consecutive movements of themotorized roller shades, and/or the minimum number N_(MIN) of shademovements per day for different areas and/or different groups ofmotorized roller shades 140 in the building. In other words, a differenttimeclock schedule may be executed for the different areas and/ordifferent groups of motorized roller shades 140 in the building (e.g.,the different façades 174 of the building).

FIG. 4 is a simplified flowchart of an example timeclock configurationprocedure 200 that may be executed periodically by a system controllerof a load control system (e.g., the system controller 110 of the loadcontrol system 100) to generate a timeclock schedule defining thedesired operation of motorized window treatments (e.g., the motorizedroller shades 140) of each façade (e.g., each linear façade) of abuilding. For example, the timeclock configuration procedure 200 may beexecuted once each day at midnight to generate a timeclock schedule forone or more areas in the building. The timeclock schedule may beexecuted between a start time t_(START) and an end time t_(END) of thepresent day. During the timeclock configuration procedure 200, thesystem controller may perform an optimal shade position procedure 300(shown in FIG. 5) for determining optimal shade positions P_(OPT)(t) ofthe motorized roller shades in response to the desired maximum sunlightpenetration distance d_(MAX) for each interval (e.g., minute) betweenthe start time t_(START) and the end time t_(END) of the present day.The system controller may then execute a timeclock event creationprocedure 400 (shown in FIG. 7) to generate the events of the timeclockschedule in response to the optimal shade positions P_(OPT)(t) and theuser-selected minimum time period T_(MIN) between shade movements.

The timeclock schedule may be split up into a number of consecutive timeintervals, each having a length equal to the minimum time period T_(MIN)between shade movements. The system controller may consider each timeinterval and determine a position to which the motorized roller shadesshould be controlled in order to prevent the sunlight penetrationdistance d_(PEN) from exceeding the desired maximum sunlight penetrationdistance d_(MAX) during the respective time interval. The systemcontroller may create events in the timeclock schedule, each having anevent time equal to the beginning of a respective time interval and acorresponding position equal to the determined position to which themotorized roller shades should be controlled in order to prevent thesunlight penetration distance d_(PEN) from exceeding the desired maximumsunlight penetration distance d_(MAX). However, the system controllermay not create a timeclock event when the determined position of aspecific time interval is equal to the determined position of apreceding time interval (as will be described in greater detail below).Therefore, the event times of the timeclock schedule may be spaced apartby multiples of the user-specified minimum time period T_(MIN) betweenshade movements.

FIG. 5 is a simplified flowchart of the optimal shade position procedure300, which may be executed by the system controller to generate theoptimal shade positions P_(OPT)(t) for each interval (e.g., minute)between the start time t_(START) and the end time t_(END) of thetimeclock schedule such that the sunlight penetration distance d_(PEN)may not exceed the desired maximum sunlight penetration distanced_(MAX). The system controller may retrieve the start time t_(START) andthe end time t_(END) of the timeclock schedule for the present day atstep 310. For example, the system controller could use an astronomicaltimeclock to set the start time t_(START) equal to the sunrise timet_(SUNRISE) for the present day, and the end time t_(END) equal to thesunset time t_(SUNSET) for the present day. Alternatively, the start andend times t_(START), t_(END) could be set to arbitrary times, e.g., 6A.M. and 6 P.M, respectively.

Next, the system controller may set a variable time t_(VAR) equal to thestart time t_(START) at step 312 and determine a worst case façade angleφ_(F-WC) at the variable time t_(VAR) to use when calculating theoptimal shade position P_(OPT)(t) at the variable time t_(VAR).Specifically, if the solar azimuth angle φ_(S) is within a façade angletolerance φ_(TOL) (e.g., approximately 3°) of the fixed façade angleφ_(F) at step 313 (e.g., if φ_(F)−φ_(TOL)≦φ_(S)≦φ_(F)+φ_(TOL)), thesystem controller may set the worst case façade angle φ_(F-WC) equal tothe solar azimuth angle φ_(S) of the façade at step 314. If the solarazimuth angle φ_(S) is not within the façade angle tolerance φ_(TOL) ofthe façade angle φ_(F) at step 313, the system controller may thendetermine if the façade angle φ_(F) plus the façade angle toleranceφ_(TOL) is closer to the solar azimuth angle φ_(S) than the façade angleφ_(F) minus the façade angle tolerance φ_(TOL) at step 315. If so, thesystem controller may set the worst case façade angle φ_(F-WC) equal tothe façade angle φ_(F) plus the façade angle tolerance φ_(TOL) at step316. If the façade angle φ_(F) plus the façade angle tolerance φ_(TOL)is not closer to the solar azimuth angle φ_(S) than the façade angleφ_(F) minus the façade angle tolerance φ_(TOL) at step 315, the systemcontroller may set the worst case façade angle φ_(F-WC) equal to thefaçade angle φ_(F) minus the façade angle tolerance φ_(TOL) at step 318.

At step 320, the system controller may use Equations 1-12 shown aboveand the worst case façade angle φ_(F-WC) to calculate the optimal shadeposition P_(OPT)(t_(VAR)) that that may be used in order to limit thesunlight penetration distance d_(PEN) to the desired maximum sunlightpenetration distance d_(MAX) at the variable time t_(VAR). At step 322,the system controller may store in the memory the optimal shade positionP_(OPT)(t_(VAR)) determined in step 320. If the variable time t_(VAR) isnot equal to the end time t_(END) at step 324, the system controller mayincrement the variable time t_(VAR) by one interval (e.g., minute) atstep 326 and determine the worst case façade angle φ_(F-WC) and theoptimal shade position P_(OPT)(t_(VAR)) for the next variable timet_(VAR) at step 320. When the variable time t_(VAR) is equal to the endtime t_(END) at step 324, the optimal shade position procedure 300 mayexit.

The system controller may generate the optimal shade positionsP_(OPT)(t) between the start time t_(START) and the end time t_(END) ofthe timeclock schedule using the optimal shade position procedure 300.FIG. 6A shows an example plot of optimal shade positions P_(OPT1)(t) ofthe motorized roller shades on a linear west-facing façade of a buildingon January 1, where the building is located at a longitude λ ofapproximately 75° W and a latitude φ of approximately 40° N. FIG. 6Bshows an example plot of optimal shade positions P_(OPT2)(t) of themotorized roller shades on a linear north-facing façade of the samebuilding on June 1. FIG. 6C shows an example plot of optimal shadepositions P_(OPT3)(t) of the motorized roller shades on a linearsouth-facing façade of the same building on April 1.

FIG. 7 is a simplified flowchart of the timeclock event creationprocedure 400, which may be executed by the system controller in orderto generate the events of the timeclock schedule. Since the timeclockschedule may be split up into a number of consecutive time intervals,the timeclock events of the timeclock schedule may be spaced between thestart time t_(START) and the end time t_(END) by multiples of theminimum time period T_(MIN) between shade movements, which may beselected by the user. During the timeclock event creation procedure 400,the system controller may generate controlled shade positionsP_(CNTL)(t), which may comprise a number of discrete events, e.g., stepchanges in the position of the motorized roller shades at the specificevent times. The system controller may use the optimal shade positionsP_(OPT)(t) from the optimal shade position procedure 300 to correctlydetermine the controlled shade positions P_(CNTL)(t) of the events ofthe timeclock schedule. The resulting timeclock schedule may include anumber of events, which may each be characterized by an event time and acorresponding preset shade position. The timeclock events may be spacedapart by periods of time that are multiples of the minimum time periodT_(MIN). The system controller may use the controlled shade positionsP_(CNTL)(t) to adjust the position of the motorized roller shades duringexecution of the timeclock schedule, e.g., between the start timet_(START) and the end time t_(END). At the end time t_(END), the systemcontroller may control the position of the motorized roller shades to anighttime position P_(NIGHT) (e.g., the fully-closed position P_(FC)).

FIG. 8A shows an example plot of controlled shade positions P_(CNTL1)(t)of the motorized roller shades on the linear west-facing façade of thebuilding on January 1 as determined during the timeclock configurationprocedure 200 of FIG. 4. FIG. 8B shows an example plot of controlledshade positions P_(CNTL2)(t) of the motorized roller shades on thelinear north-facing façade of the building on June 1 as determinedduring the timeclock configuration procedure 200 of FIG. 4. FIG. 8Cshows an example plot of controlled shade positions P_(CNTL3)(t) of themotorized roller shades on the linear south-facing façade of thebuilding on April 1 as determined during the timeclock configurationprocedure 200 of FIG. 4.

The system controller may examine the values of the optimal shadepositions P_(OPT)(t) during each of the time intervals of the timeclockschedule (e.g., the time periods between two consecutive timeclockevents) to determine the lowest shade position P_(LOW) during each ofthe time intervals. During the timeclock event creation procedure 400,the system controller may use two variable times t_(V1), t_(V2) todefine the endpoints of the time interval that the system controller ispresently examining. The system controller may use the variable timest_(V1), t_(V2) to sequentially step through the events of the timeclockschedule, which may be spaced apart by the minimum time period T_(MIN).The system controller may set the event times of the timeclock eventsequal to the beginning of the respective time interval (e.g., the firstvariable time t_(V1)), and the controlled shade positions P_(CNTL)(t) ofthe timeclock events equal to the lowest shade positions P_(LOW) duringthe respective time intervals.

Referring to FIG. 7, the system controller may set the first variabletime t_(V1) equal to the start time t_(START) of the timeclock scheduleat step 410. The system controller may also initialize a previous shadeposition P_(PREV) to the nighttime position P_(NIGHT) at step 410. Ifthere is enough time left before the end time t_(END) for the presenttimeclock event (e.g., if the first variable time t_(V1) plus theminimum time period T_(MIN) is not greater than the end time t_(END)) atstep 412, the system controller may determine at step 414 if there isenough time for another timeclock event in the timeclock schedule afterthe present timeclock event. If the first variable time t_(V1) plus twotimes the minimum time period T_(MIN) is not greater than the end timet_(END) at step 414, the system controller may set the second variabletime t_(V2) equal to the first variable time t_(V1) plus the minimumtime period T_(MIN) at step 416, such that the system controller maythen examine the time interval between the first and second variabletimes t_(V1), t_(V2). If the first variable time t_(V1) plus two timesthe minimum time period T_(MIN) is greater than the end time t_(END) atstep 414, the system controller may set the second variable time t_(V2)equal to the end time t_(END) at step 418, such that the systemcontroller may then examine the time interval between the first variabletime t_(V1) and the end time t_(END).

At step 420, the system controller may determine the lowest shadeposition P_(LOW) of the optimal shade positions P_(OPT)(t) during thepresent time interval (e.g., between the first variable time t_(V1) andthe second variable time t_(V2) determined at steps 416 and 418). If, atstep 422, the previous shade position P_(PREV) is not equal to thelowest shade position P_(LOW) during the present time interval (asdetermined at step 420), the system controller may set the controlledposition P_(CNTL)(t_(V1)) at the first variable time t_(V1) to be equalto the lowest shade position P_(LOW) of the optimal shade positionsP_(OPT)(t) during the present time interval at step 424. The systemcontroller may then store in memory a timeclock event having the eventtime t_(V1) and the corresponding controlled position P_(CNTL)(t_(V1))at step 426 and set the previous shade position P_(PREV) equal to thedetermined controlled position P_(CNTL)(t_(V1)) at step 428. If, at step422, the previous shade position P_(PREV) is equal to the lowest shadeposition P_(LOW) during the present time interval, the system controllermay not create a timeclock event at the first variable time t_(V1). Thesystem controller may then begin to examine the next time interval bysetting the first variable time t_(V1) equal to the second variable timet_(V2) at step 430. The timeclock event creation procedure 400 loopsaround such that the system controller may determine if there is enoughtime left before the end time t_(END) for the present timeclock event atstep 412. If the first variable time t_(V1) plus the minimum time periodT_(MIN) is greater than the end time t_(END) at step 412, the systemcontroller may enable the timeclock schedule at step 432 and thetimeclock event creation procedure 400 may exit.

FIG. 9 is a simplified flowchart of a timeclock schedule executionprocedure 500, which may be executed by the system controllerperiodically, e.g., every minute between the start time t_(START) andthe end time t_(END) of the timeclock schedule. Since there may bemultiple timeclock schedules for the motorized roller shades controlledby each of the system controllers, each system controller may executethe timeclock schedule execution procedure 500 multiple times, e.g.,once for each timeclock schedule. During the timeclock scheduleexecution procedure 500, the system controller may adjust the positionsof the motorized roller shades to the controlled positions P_(CNTL)(t)determined in the timeclock event creation procedure 400.

In some cases, when the system controller controls the motorized rollershades to the fully-open positions P_(FO) (e.g., when there is no directsunlight incident on the façade), the amount of daylight entering thespace may be unacceptable to a user of the space. Therefore, the systemcontroller may be configured to set the open-limit positions of themotorized roller shades of one or more of the spaces or façades of thebuilding to a visor position P_(VISOR), which may be lower than thefully-open position P_(FO), but may be equal to the fully-open position.Thus, the visor position P_(VISOR) may define the highest position towhich the motorized roller shades may be controlled during the timeclockschedule. The position of the visor position P_(VISOR) may be enteredusing the GUI software of the network device. In addition, the visorposition P_(VISOR) may be enabled and disabled for each of the spaces orfaçades of the building using the GUI software of the network device.Since two adjacent windows of the building may have different heights,the visor positions P_(VISOR) of the two windows may be programmed usingthe GUI software, such that the hembars of the shade fabrics coveringthe adjacent window are aligned when the motorized roller shades arecontrolled to the visor positions P_(VISOR).

Referring to FIG. 9, if the timeclock schedule is enabled at step 510,the system controller may determine the time t_(NEXT) of the nexttimeclock event from the timeclock schedule at step 512. If the presenttime t_(PRES) is equal to the next event time t_(NEXT) at step 514 andthe controlled position P_(CNTL)(t_(NEXT)) at the next event timet_(NEXT) is greater than or equal to the visor position P_(VISOR) atstep 516, the system controller may adjust the positions of themotorized roller shades to the visor position P_(VISOR) at the nextevent time t_(NEXT) at step 518. Otherwise, the system controller mayadjust the positions of the motorized roller shades to the controlledposition P_(CNTL)(t_(NEXT)) at the next event time t_(NEXT) at step 520.After adjusting the positions of the motorized roller shades at steps518, 520, after determining that there is not a timeclock event at thepresent time at step 514, or after determining that the timeclockschedule is not enabled at step 510, the system controller may make adetermination as to whether the present time is equal to the end timet_(END) of the timeclock schedule at step 524. If not, the timeclockschedule execution procedure 500 may simply exit. If the present time isequal to the end time t_(END) at step 524, the system controller maycontrol the motorized roller shades to the nighttime position P_(NIGHT)at step 526 and disables the timeclock schedule at step 528, before thetimeclock schedule execution procedure 500 may exit.

Accordingly, the system controller may control the motorized rollershades to limit the sunlight penetration distance d_(PEN), whileminimizing occupant distractions, by adjusting the motorized rollershades at times that are spaced apart by multiples of the user-specifiedminimum time period T_(MIN) between shade movements. Since the positionsof the motorized roller shades in the building may each be adjusted atthese specific times (e.g., at the multiples of the user-specifiedminimum time period T_(MIN)), the motorized roller shades may each moveat the same times during the timeclock schedule, thus minimizingoccupant distractions. Even adjustments of adjacent motorized rollershades located on different façades (for example, in a corner office)may move at the same times (e.g., at the multiples of the user-specifiedminimum time period T_(MIN)). If the minimum time period T_(MIN) betweenshade movements is chosen to be a logical time period (e.g., one hour),the users of the building may know when to expect movements of themotorized roller shades, and thus may not be as distracted by the shademovements as compared to shade movements occurring at random times.Alternatively, the GUI software of the network device could allow theuser to select the specific event times of the timeclock events (whileensuring that the minimum time period T_(MIN) exists between consecutivetimeclock events) in order to conform the timeclock schedule to apredetermined time schedule. For example, the event times of thetimeclock schedule could be chosen according to a class schedule at aschool building, such that the motorized roller shades may move betweenthe periods of the class schedule.

Since the timeclock configuration procedure 200 shown in FIG. 4 uses asmall number of inputs in order to automatically generate a timeclockschedule, the operation of the motorized roller shades may be easily andquickly reconfigured using the GUI software of the network device. Whilethe local longitude λ and latitude φ of the building, the façade angleφ_(F) for a specific façade of the building, the height h_(WIN) of thewindow in a specific space, and/or the height h_(WORK) of the table inthe specific space of the building will not typically change afterinstallation and configuration of the load control system 100, the usermay just adjust the desired maximum sunlight penetration distanced_(MAX) and/or the minimum time period T_(MIN) between shade movementsto adjust the operation of the motorized window shades in the spaceoccupied by the user. The GUI software of the network device providesscreens to allow for adjustment of the desired maximum sunlightpenetration distance d_(MAX) and/or the minimum time period T_(MIN)between shade movements. After an adjustment of the desired maximumsunlight penetration distance d_(MAX) and/or the minimum time periodT_(MIN) between shade movements, the network device may transmit theupdated operational characteristics to the system controllers 110, andthe system controllers may each generate a subsequent timeclock scheduleusing the timeclock configuration procedure 200 and immediately beginoperating based on the subsequent timeclock schedule. The user canrepetitively adjust the desired maximum sunlight penetration distanced_(MAX) and the minimum time period T_(MIN) between shade movements(e.g., use an iterative process) over the course of multiple days inorder to achieve the desired operation of the motorized roller shades140 in the space.

The motorized roller shades 140 may be controlled such that the hembars184 (FIG. 2) of each of the motorized roller shades on one of thefaçades 174 of the building may be aligned (e.g., positioned atapproximately the same vertical position) at each time during thetimeclock schedule. Since each of the motorized roller shades 140 on afaçade are adjusted at the same time, the system controller maycalculate the same controlled position P_(CNTL)(t) for each of themotorized roller shades on the façade at a specific event time (assumingthat each of the motorized roller shades are controlled to limit thesunlight penetration distance d_(PEN) to the same desired maximumsunlight penetration distance d_(MAX)). Therefore, the hembars 184 ofthe motorized roller shades 140 on a façade may be aligned independentof differences in the size, shape, or height of the windows of thefaçade.

FIG. 10 is a simplified flowchart of another example timeclockconfiguration procedure 600 that may be executed periodically by asystem controller of a load control system (e.g., the system controller110 of the load control system 100) to generate a timeclock scheduledefining the desired operation of motorized window treatments (e.g., themotorized roller shades 140) of each façade of a building. During thetimeclock configuration procedure 600 of FIG. 10, the system controllermay generate a timeclock schedule in response to a maximum numberN_(MAX) of movements of the motorized roller shades 140 that may occurduring the present day, as well as in response to the minimum timeperiod T_(MIN) that may exist between any two consecutive movements ofthe motorized roller shades. The timeclock schedule may provide forcontrol of the motorized roller shades 140 to limit the sunlightpenetration distance d_(PEN) to be less than the desired maximumsunlight penetration distance d_(MAX).

The desired maximum sunlight penetration distance d_(MAX), the maximumnumber N_(MAX) of roller shade movements, and the minimum time periodT_(MIN) between shade movements may be stored in the memory in thesystem controller and may be entered by a user using the GUI software ofthe network device. For example, the maximum number N_(MAX) of rollershade movements may have a minimum value of approximately three.Accordingly, the user may be able to control the maximum number N_(MAX)of roller shade movements and the minimum time period T_(MIN) betweenshade movements in order to minimize distractions of an occupant in thespace due to roller shade movements. The user may select differentvalues for the desired maximum sunlight penetration distance d_(MAX),the maximum number N_(MAX) of roller shade movements, and/or the minimumtime period T_(MIN) between shade movements for different areas anddifferent groups of motorized roller shades 140 in the building.

During the timeclock configuration procedure 600, the system controllermay first perform the optimal shade position procedure 300 fordetermining the optimal shade positions P_(OPT)(t) of the motorizedroller shades 140 in response to the desired maximum sunlightpenetration distance d_(MAX) for each interval (e.g., minute) betweenthe start time t_(START) and the end time t_(END) of the present day (asdescribed above with reference to FIG. 5). The system controller maythen execute a timeclock event creation procedure 700 (shown in FIGS.11A-11C) to generate the events of the timeclock schedule in response tothe optimal shade positions P_(OPT)(t), the maximum number N_(MAX) ofroller shade movements, and the minimum time period T_(MIN) betweenshade movements. Referring to FIGS. 6A-6C, the plots of the optimalshade positions P_(OPT1)(t), P_(OPT2)(t), P_(OPT3)(t) may each include adifferent number of “flat regions” 350 and “movement regions” 355. Aflat region is defined as a portion of a plot of the optimal shadepositions P_(OPT)(t) that does not change in position for at least theminimum time period T_(MIN). A movement region is defined as a portionof a plot of the optimal shade positions P_(OPT)(t) during which theposition changes (e.g., between two flat regions 350). The systemcontroller may analyze the flat regions and the movement regions of theplots of the optimal shade positions P_(OPT1)(t), P_(OPT2)(t),P_(OPT3)(t) in order to determine the event times of the timeclockschedule. During the timeclock event creation procedure 700, the systemcontroller may generate controlled shade positions P_(CNTL)(t), whichmay comprise a number of discrete changes in the position of themotorized roller shades at the specific event times.

Referring back to FIG. 10, the system controller may conclude thetimeclock configuration procedure 600 by executing a timeclock eventoptimization procedure 800 to optimize the operation of the timeclockschedule by eliminating unnecessary timeclock events. The events of theresulting timeclock schedule may occur at any time between the starttime t_(START) and the end time t_(END), as long as two consecutiveevents do not occur within the minimum time period T_(MIN) and thenumber of timeclock events does not exceed the maximum number N_(MAX) ofroller shade movements. The controlled shade positions P_(CNTL)(t) ofthe resulting timeclock schedule may be used by the system controller toadjust the position of the motorized roller shades during the timeclockschedule execution procedure 500 (as shown in FIG. 9).

FIG. 13A shows an example plot of controlled shade positionsP_(CNTL4)(t) of the motorized roller shades on the west façade of thebuilding on January 1 as determined during the timeclock configurationprocedure 600 of FIG. 10. FIG. 13B shows an example plot of controlledshade positions P_(CNTL5)(t) of the motorized roller shades on the northfaçade of the building on June 1 as determined during the timeclockconfiguration procedure 600 of FIG. 10. FIG. 13C shows an example plotof controlled shade positions P_(CNTL6)(t) of the motorized rollershades on the south façade of the building on April 1 as determinedduring the timeclock configuration procedure 600 of FIG. 10.

FIGS. 11A-11C are simplified flowcharts of the timeclock event creationprocedure 700, which may be executed by the system controller in orderto generate the events of the timeclock schedule during the timeclockconfiguration procedure 600 shown in FIG. 10. The system controller mayset a variable N equal to the maximum number N_(MAX) of roller shademovements at step 710. The system controller may use the variable N tokeep track of how many more timeclock events may be generated withoutexceeding the maximum number N_(MAX). The system controller maydetermine the number N_(FR) of flat regions of the optimal shadepositions P_(OPT)(t) between the start time t_(START) and the end timet_(END) at step 712, and then generate timeclock events at the beginningof each of the flat regions. The system controller may begin byconsidering the first flat region at step 714, before determining thebeginning time t_(FR1) and the end time t_(FR2) of the first flat regionat step 716 and determining the constant shade position P_(FR)associated with the first flat region at step 718. If the first flatregion does not begin less than the minimum time period T_(MIN) afterthe start time t_(START) (e.g., if t_(FR1)−t_(START)≧T_(MIN)) at step720, the system controller may generate an event at the beginning of theflat region at step 722. Specifically, the system controller may set thecontrolled shade position P_(CNTL)(t_(FR1)) at the beginning timet_(FR1) of the first flat region to be equal to the optimal shadeposition P_(OPT)(t_(FR1)) at the beginning time t_(FR1) at step 722 anddecrement the variable N by one at step 724 (e.g., as shown at timet_(FR1) in FIG. 13C).

If the first flat region begins less than the minimum time periodT_(MIN) after the start time t_(START) (e.g., ift_(FR1)−t_(START)<T_(MIN)) at step 720, the system controller maydetermine the lowest shade position P_(LOW) of the optimal shadeposition P_(OPT)(t_(START)) between the start time t_(START) of thetimeclock schedule and the beginning time t_(FR1) of the flat region atstep 726. If the lowest shade position P_(LOW) is not equal to theconstant shade position P_(FR) of the flat region at step 728 (e.g., ifthe plot of the optimal shade positions P_(OPT)(t) is moving downward atthe start time t_(START)), the system controller may set the controlledshade position P_(CNTL)(t_(START)) at the start time t_(START) of thetimeclock schedule to be equal to the constant shade position P_(FR) ofthe flat region at step 730 and decrement the variable N by one at step732. If the lowest shade position P_(LOW) is equal to the constant shadeposition P_(FR) of the flat region at step 728 (e.g., if the plot of theoptimal shade positions P_(OPT)(t) is moving upward at the start timet_(START)), the system controller may set the controlled shade positionP_(CNTL)(t_(START)) at the start time t_(START) of the timeclockschedule to be equal to the lowest shade position P_(LOW) at step 734.If the present flat region is too small to create another timeclockevent before the end time t_(FR2) of the flat region (e.g., ift_(FR2)<t_(START)+2·T_(MIN)) at step 735, the system controller maysimply decrement the variable N by one at step 724.

However, if the present flat region is long enough to create anothertimeclock event before the end time t_(FR2) of the flat region (e.g., ift_(FR2)≧t_(START)+2·T_(MIN)) at step 735, the system controller may setthe controlled shade position P_(CNTL)(t_(START)+T_(MIN)) to be equal tothe constant shade position P_(FR) of the flat region at a time that isthe minimum time period T_(MIN) after the start time t_(START) (e.g.,t_(START)+T_(MIN)) at step 736, and decrement the variable N by two atstep 738. After generating timeclock events at steps 722, 730, 734, 736,the system controller may determine if there are more flat regions toconsider at step 740. If so, the system controller may consider the nextflat region at step 742, before determining the beginning time t_(FR1)of the next flat region at step 716, determining the constant shadeposition P_(FR) associated with the next flat region at step 718, andgenerating appropriate timeclock events at steps 722, 730, 734, 736.

Referring to FIG. 11B, if there are not more flat regions to consider atstep 740, and the variable N is equal to zero at step 744 (e.g., thenumber of events generated so far is equal to the maximum number N_(MAX)of roller shade movements), the system controller may determine if thereshould be one or more timeclock events during the movement regions(rather than those timeclock events created for the flat regions atsteps 722, 730, 734, 736). Specifically, the system controller mayconsiders the first lowering movement regions (e.g., a movement regionduring which the position of the motorized roller shade is movingtowards 0%) at step 746, and determines the start time t_(MR1) and theend time t_(MR2) of the first lowering movement region at step 748.Next, the system controller may determine the lowest shade positionP_(LOW) of the optimal shade positions P_(OPT)(t) during the presentlowering movement region (e.g., between the time t_(MR1) and the timet_(MR2)) at step 750. At step 752, the system controller may then setthe controlled shade position P_(CNTL)(t_(MR1)) at the beginning timet_(MR1) of the present movement region to be equal to the lowest shadeposition P_(LOW) of the optimal shade positions P_(OPT)(t) during thepresent lowering movement region as determined in step 750 (e.g., asshown at time t_(E6) in FIG. 13A). If there are more lowering movementregions to consider at step 754, the system controller may consider thenext lowering movement region at step 756, and the timeclock eventcreation procedure 700 may loop around, to create a timeclock event forthe next lowering movement region. If there are not more loweringmovement regions to consider at step 754, the timeclock event creationprocedure 700 may exit.

Referring to FIG. 11C, if the variable N is not equal to zero at step744 (e.g., the number of events generated so far is greater than themaximum number N_(MAX) of roller shade movements), the system controllermay generate timeclock events during the movement regions of the optimalshade positions P_(OPT)(t). At step 760, the system controller maycalculate the total combined length T_(TOTAL) of the movement regions.Next, the system controller may determine if the user-selected maximumnumber N_(MAX) of roller shade movements or the user-selected minimumtime period T_(MIN) between shade movements is the limiting factor fordetermining a movement time T_(MOVE), which may exist between thetimeclock schedule events during the movement regions (e.g., as shown inFIG. 13B). Specifically, if the total combined length T_(TOTAL) of themovement regions divided by the variable N (e.g., the number ofremaining possible shade movements) is less than the minimum time periodT_(MIN) at step 762, the minimum time period T_(MIN) may be the limitingfactor and thus the system controller may set the movement time T_(MOVE)equal to the minimum time period T_(MIN) at step 764. If the totalcombined length T_(TOTAL) of the movement regions divided by thevariable N is not less than the minimum time period T_(MIN) at step 762,the number of remaining possible shade movements (e.g., the variable N)may be the limiting factor and thus the system controller may set themovement time T_(MOVE) equal to the total combined length T_(TOTAL) ofthe movement regions divided by the variable N at step 766.

Next, the system controller may generate timeclock events during themovement regions of the optimal shade positions P_(OPT)(t). The systemcontroller may consider the first movement region at step 768, determinethe start time t_(MR1) and the end time t_(MR2) of the first movementregion at step 770, and set a variable m to zero at step 772. At step774, the system controller may consider a time segment that begins at atime t_(S1) and ends at a time t_(S2) as defined by:

t _(S1) =t _(MR1) +m·T _(MOVE); and  (Equation 13)

t _(S2) =t _(MR1)+1)·T _(MOVE).  (Equation 14)

If the time t_(S2) of the present time segment is within the minimumtime period T_(MIN) of the end time t_(MR2) of the present movementregion at step 776 (e.g., if t_(MR2)−t_(S2)<T_(MIN)), a timeclock eventmay not be generated between the time t_(S2) of the present time segmentand the end time t_(MR2) of the present movement region. Therefore, thesystem controller may set the time t_(S2) of the present time segmentequal to the end time t_(MR2) of the present movement region at step778.

After the time t_(S2) of the present time segment is set equal to theend time t_(MR2) of the present movement region at step 778, or if thetime t_(S2) of the present time segment is not within the minimum timeperiod T_(MIN) of the end time t_(MR2) of the present movement region atstep 776 (e.g., if t_(MR2)−t_(S2)≧T_(MIN)), the system controller maydetermine the lowest shade position P_(LOW) of the optimal shadepositions P_(OPT)(t) during the present time segment (e.g., between thetime t_(S1) and the time t_(S2)) at step 780. At step 782, the systemcontroller may then set the controlled shade position P_(CNTL)(t_(S1))at the time t_(S1) to be equal to the lowest shade position P_(LOW) ofthe optimal shade positions P_(OPT)(t) during the present time segmentas determined in step 780 (e.g., as shown at time t_(E2) in FIG. 13B).If the time t_(S2) of the present time segment is not equal to the endtime t_(MR2) of the present movement region at step 784, the systemcontroller may increment the variable m at step 786, consider the nexttime segment at step 774, and generate another timeclock event at step782. However, if the time t_(S2) of the present time segment is equal tothe end time t_(MR2) of the present movement region at step 784 andthere are more movement regions to consider at step 788, the systemcontroller may consider the next movement region at step 790, and thetimeclock event creation procedure 700 may loop around, such that thesystem controller may generate the timeclock events for the nextmovement region. If there are not more movement regions to consider atstep 788, the timeclock event creation procedure 700 may exit.

FIG. 12 is a simplified flowchart of the timeclock event optimizationprocedure 800, which may be executed by the system controller in orderto optimize the operation of the timeclock schedule by eliminatingunnecessary timeclock events during the timeclock configurationprocedure 600 of FIG. 10. If there is more than one event in thetimeclock schedule at step 810, the system controller may set a previousposition variable P_(PREV) to be equal to the controlled shade positionP_(CNTL)(t_(START)) at the start time t_(START) at step 812. The systemcontroller may then determine a next event time t_(NEXT) of thetimeclock schedule at step 814, and set a present position variableP_(PRES) equal to the controlled shade position P_(CNTL)(t_(NEXT)) atthe next event time t_(NEXT) at step 816. If the present positionvariable P_(PRES) is within a minimum shade position distance ΔP_(MIN)(e.g., 5%) of the previous position variable P_(PREV) at step 818, thesystem controller may eliminate the present event at time t_(NEXT) atstep 820. For example, the events at times t_(E2) and/or t_(E6) of thecontrolled shade position P_(CNTL1)(t) in FIG. 13A may be eliminated. Ifthe present position variable P_(PRES) is greater than the minimum shadeposition distance ΔP_(MIN) away from the previous position variableP_(PREV) at step 818, the system controller may keep the present eventat time t_(NEXT) and may set the previous position variable P_(PREV)equal to the present position variable P_(PRES) at step 822. If thereare more events in the timeclock schedule at step 824, the systemcontroller may determine the next event time t_(NEXT) of the timeclockschedule at step 814, and set the present position variable P_(PRES)equal to the controlled shade position P_(CNTL)(t_(NEXT)) at the nextevent time t_(NEXT) at step 816, before determining whether to eliminatethe present event at step 820. If there are not more events in thetimeclock schedule at step 824, the system controller may enable thetimeclock schedule at step 826 and the timeclock event optimizationprocedure 800 may exit.

Alternatively, the system controller may not generate a timeclockschedule prior to controlling the motorized roller shade 140 duringnormal operation in order to prevent the sunlight penetration distanced_(PEN) from exceeding the desired maximum sunlight penetration distanced_(MAX) while minimizing user distractions. The system controller maycalculate the positions to which to control the motorized roller shades140 “on-the-fly”, e.g., immediately before adjusting the positions ofthe motorized roller shades. The system controller may adjust thepositions of the motorized roller shades 140 periodically, e.g., attimes spaced apart by multiples of the minimum time period T_(MIN) thatmay exist between any two consecutive movements of the motorized rollershades. Accordingly, the system controller may control the positions ofthe motorized roller shades 140 to positions similar to the controlledshade positions P_(CNTL1)(t), P_(CNTL2)(t), P_(CNTL3)(t) of thetimeclock configuration procedure 200 (e.g., as shown in FIGS. 8A-8C).

FIG. 14 is a simplified top view of an example of a load control system900 installed in a space 902 (e.g., an office space or room in aresidence) of a building having a non-linear façade 904. For example,the non-linear façade 904 may be curved and may include a number ofwindows 906 (e.g., curved windows) for allowing sunlight to enter thespace 902. Alternatively, the windows 906 may be straight and/or thefaçade 904 may be arranged in some other continuously-curved orpiecewise non-linear shape. In addition, the non-linear façade 904 couldalternatively comprise two or more adjacent linear façades (e.g., acompound façade). The space 902 may also comprise a number of worksurfaces, e.g., tables 908. A motorized window treatment, e.g., amotorized roller shade 910 (such as the motorized roller shade 140 shownin FIGS. 1 and 2), may be mounted adjacent each one of the windows 906to control the amount of daylight entering the space 902. Each motorizedroller shade 910 may comprise a respective electronic drive unit 912 formoving a shade fabric of the motorized roller shade to adjust the amountof daylight entering the space 902. The motorized roller shades 910shown in FIG. 14 are arranged along a portion of the total façade of thebuilding (e.g., a quarter of the total façade of a cylindrical building)that extends clockwise from a start façade angle φ_(START) and an endfaçade angle φ_(END) (e.g., approximately 180° and 270°, respectively).The load control system 900 may comprise additional motorized rollershades 910 located in other parts and/or floors of the building.

The load control system 900 may further comprise a system controller,e.g., a shade controller 920, which may be coupled to the electronicdrive units 912 of the motorized roller shades 910 via a communicationlink, e.g., a wired digital communication link 922. The shade controller920 may be configured to control the motorized roller shades 910 tocontrol a sunlight penetration distance d_(PEN) in the space 902. Theshade controller 920 may comprise an astronomical timeclock fordetermining a sunrise time t_(SUNRISE) and a sunset time t_(SUNSET) foreach day of the year at the location of the building. The shadecontroller 920 may transmit digital messages to the electronic driveunits 912 via the digital communication link 922 to automaticallycontrol the motorized roller shades 910 in response to a timeclockschedule (e.g., that may be executed between the sunrise timet_(SUNRISE) and a sunset time t_(SUNSET)). For example, the shadecontroller 920 may control the motorized roller shades 910 to limit thesunlight penetration distance d_(PEN) in the space 902 to a desiredmaximum sunlight penetration distance d_(MAX) in the direction of thesun (e.g., along the solar azimuth angle φ_(S)). Alternatively, thecommunication link between the shade controller 920 and the electronicdrive units 912 could comprise a wireless communication link, such as aradio-frequency (RF) communication link or an infrared (IR)communication link.

The shade controller 920 may control the motorized roller shades 910 inone or more groups, such that all of the motorized roller shades in asingle group move at the same time to the same positions, whichminimizes occupant distractions and improves the aesthetic appearance ofthe shade fabric of the motorized roller shades 910. For example, theshade controller 920 may control the motorized roller shades 910 in oneor more groups. The motorized roller shades 910 of a single group of theload control system 900 may be located adjacent to each other along aportion of the total façade of the building, for example, along aquarter of the total façade as shown in FIG. 14. The portion of thecurved façade adjacent each group of shades may be characterized by atleast two distinct façade angles (e.g., the start façade angle φ_(START)and an end façade angle φ_(END) as shown in FIG. 14). Each of themotorized roller shades 910 may be oriented at an angle between (orequal to) the start façade angle φ_(START) and the end façade angleφ_(END) (e.g., as shown by an example shade-façade angle φ_(F-SHADE) inFIG. 14).

FIG. 15 is a simplified flowchart of an example timeclock configurationprocedure 1000 that may be executed periodically by a system controllerof a load control system (e.g., the shade controller 920 of the loadcontrol system 900 shown in FIG. 21). For example, the timeclockconfiguration procedure 1000 may be executed by the shade controller 920before the beginning of each day to build a timeclock schedule forcontrolling the motorized roller shades 910 during that coming day.During an optimal shade position procedure 1010, the shade controller920 may calculate the solar azimuth angle φ_(S) using the locallongitude and latitude of the building and the present local time anddate. The shade controller 920 may use the solar azimuth angle φ_(S),the solar elevation angle θ_(S), and the at least two distinct façadeangles of the curved façade 904 to determine optimal shade positionsP_(OPT)(t) of the motorized roller shades 910 that will limit thesunlight penetration distance d_(PEN) in the space 902 to the desiredmaximum sunlight penetration distance d_(MAX) for each interval (e.g.,minute) between a start time t_(START) and an end time t_(END) of thetimeclock schedule. The shade controller 920 may use the optimal shadepositions P_(OPT)(t) to build the timeclock schedule during a timeclockevent creation procedure 1020 (e.g., in a similar manner as in thetimeclock event creation procedure 400 shown in FIG. 7). Each of themotorized roller shades 910 of the group may be controlled to the samepositions in response to the timeclock schedule.

For example, during the optimal shade position procedure 1010, the shadecontroller 920 may use a shade-façade angle φ_(F-SHADE) of each of themotorized roller shades 910 in the group to calculate the optimal shadepositions P_(OPT)(t) for each motorized roller shade in the group foreach interval (e.g., minute) of the timeclock schedule. The shadecontroller 920 may then pick the lowest position of the optimal shadepositions P_(OPT)(t) of each motorized roller shade in the group to bean optimal shade group position P_(OPT-G)(t) at each interval (e.g.,minute) of the timeclock schedule. The shade controller 920 may use theoptimal shade group positions P_(OPT-G)(t) to build the timeclockschedule during the timeclock event creation procedure 1020.

The shade controller 920 could alternatively use the start façade angleφ_(START) and the end façade angle φ_(END) of the non-linear façade(e.g., as shown in FIG. 14) to calculate respective optimal shadepositions φ_(START)(t), φ_(END)(t) at each end of the portion of thefaçade along which the motorized roller shades are oriented. The shadecontroller 920 could then pick the lowest position of the start and endoptimal shade positions φ_(START)(t), φ_(END)(t) to be an optimal shadegroup position P_(OPT-G)(t) at each interval (e.g., minute) of thetimeclock schedule. In addition, the shade controller 920 couldalternatively use the shade-façade angles φ_(F-SHADE) of the motorizedroller shades at each end of the portion of the non-linear façade alongwhich the group of motorized roller shades are arranged to calculate theoptimal shade positions φ_(START)(t), φ_(END)(t).

Alternatively, the shade controller 920 could determine a representativefaçade angle φ_(F-REP) from the at least two distinct façade angles ofthe curved façade (e.g., the start angle φ_(START) and the end angleφ_(END)) and then use the representative façade angle φ_(F-REP) tocalculate the optimal shade positions P_(OPT)(t) for the motorizedroller shades in the group for each interval (e.g., minute) of thetimeclock schedule. The representative façade angle φ_(F-REP) may be afunction of the solar azimuth angle φ_(S) and may represent theworst-case solar penetration into the space. For example, the systemcontroller 920 may recalculate the representative façade angle φ_(F-REP)for each interval (e.g., minute) between the start time t_(START) andthe end time t_(END) of the timeclock schedule to determine the optimalshade positions P_(OPT)(t).

FIG. 16 is a simplified flowchart of an example optimal shade positionprocedure 1100 that may be executed by a system controller to determineoptimal shade group positions P_(OPT-G)(t) for a plurality of motorizedwindow treatments (e.g., motorized roller shades) arranged along anon-linear façade (or multiple adjacent linear façades) of a building tolimit the sunlight penetration distance d_(PEN) in a space of thebuilding to a desired maximum sunlight penetration distance d_(MAX) foreach interval (e.g., minute) between a start time t_(START) and an endtime t_(END) of a timeclock schedule. For example, the optimal shadeposition procedure 1100 may be executed by the shade controller 920 ofthe load control system 900 during the timeclock configuration procedure1000 shown in FIG. 15. At step 1110, the system controller may retrievea start time t_(START) and an end time t_(END) of the timeclock schedulefor the present day, e.g., using an astronomical timeclock to set thestart time t_(START) equal to the sunrise time t_(SUNRISE) for thepresent day, and the end time t_(END) equal to the sunset timet_(SUNSET) for the present day. The system controller may set a variabletime t_(VAR) equal to the start time t_(START) at step 1112.

During the optimal shade position procedure 1100, the system controllermay use two distinct façade angles (e.g., the start façade angleφ_(START) and the end façade angle φ_(END) of the non-linear façade) tocalculate the optimal shade group positions P_(OPT-G)(t). Specifically,at step 1114, the system controller may determine a start-angle optimalshade position φ_(START)(t_(VAR)) that may be used in order to limit thesunlight penetration distance d_(PEN) to the desired maximum sunlightpenetration distance d_(MAX) at the variable time t_(VAR) and at thestart façade angle φ_(START) (e.g., using Equations 1-12 shown above).At step 1116, the system controller may determine an end-angle optimalshade position φ_(END)(t_(VAR)) that may be used in order to limit thesunlight penetration distance d_(PEN) to the desired maximum sunlightpenetration distance d_(MAX) at the variable time t_(VAR) and at the endfaçade angle φ_(END). Alternatively, the system controller could use theshade-façade angles φ_(F-SHADE) of the motorized roller shades at eachend of the portion of the non-linear façade along which the group ofmotorized roller shades are arranged at steps 1114 and 1116.

The system controller may determine a lowest optimal shade positionP_(LOW)(t_(VAR)), for example, the lowest of the start-angle optimalshade position φ_(START)(t_(VAR)) and the end-angle optimal shadeposition φ_(END)(t_(VAR)) at step 1118. At step 1120, the systemcontroller may store the lowest optimal shade position P_(LOW)(t_(VAR))in memory as the optimal shade group position P_(OPT-G)(t_(VAR)) at thevariable time t_(VAR) (e.g., to be used in the timeclock event creationprocedure 1020 of the timeclock configuration procedure 1000 shown inFIG. 15). If the variable time t_(VAR) is not equal to the end timet_(END) at step 1122, the system controller may increment the variabletime t_(VAR) by one interval (e.g., minute) at step 1124 and determinethe optimal shade group position P_(OPT-G)(t_(VAR)) for the nextvariable time t_(VAR) for being stored at step 1120. When the variabletime t_(VAR) is equal to the end time t_(END) at step 1122, the optimalshade position procedure 1100 may exit.

FIG. 17 is a simplified flowchart of another example optimal shadeposition procedure 1200 that may be executed by a system controller todetermine optimal shade group positions for a plurality of motorizedwindow treatments (e.g., a number N_(SHADES) of motorized roller shades)arranged along a non-linear façade (or multiple adjacent linear façades)of a building. For example, the optimal shade position procedure 1200may be executed by the shade controller 920 of the load control system900 during the timeclock configuration procedure 1000 shown in FIG. 15.The system controller may retrieve a start time t_(START) and an endtime t_(END) of a timeclock schedule for the present day at step 1210and then set a variable time t_(VAR) equal to the start time t_(START)at step 1212.

During the optimal shade position procedure 1200, the system controllermay use the shade-façade angle φ_(F-SHADE) of each of the motorizedroller shades in the group to calculate the optimal shade grouppositions P_(OPT-G)(t). For each interval (e.g., minute) between thestart time t_(START) and the end time t_(END) of the timeclock schedule,the system controller may step through each of the motorized rollershades in the group and calculate the optimal shade positionP_(OPT)(t_(VAR)) using the shade-façade angle φ_(F-SHADE) for therespective motorized roller shade. The system controller may use avariable n to keep track of which of the motorized roller shades ispresently being analyzed (e.g., ranging from one up to the numberN_(SHADES) of motorized roller shades). Referring back to FIG. 17, thesystem controller may set the variable n equal to one at step 1214, andrecall the shade-façade angle φ_(F-SHADE) for motorized roller shade nat step 1216. For example, the system controller may recall theshade-façade angle φ_(F-SHADE) of the first motorized roller shade inthe group the first time step 1216 is executed.

At step 1218, the system controller may determine an optimal shadeposition P_(OPT)(t_(VAR)) that may be used in order to limit thesunlight penetration distance d_(PEN) to the desired maximum sunlightpenetration distance d_(MAX) at the variable time t_(VAR) and at theshade-façade angle φ_(F-SHADE) for motorized roller shade n and storethe optimal shade position P_(OPT)(t_(VAR)) in memory. If there are moreshades in the group (e.g., if the variable n is not equal to the numberN_(SHADES)) at step 1220, the system controller may increment thevariable n at step 1222, recall the shade-façade angle φ_(F-SHADE) formotorized roller shade n at step 1216, and determine the optimal shadeposition P_(OPT)(t_(VAR)) for motorized roller shade n at step 1218.

If there are not more motorized roller shades in the group (e.g., if thevariable n is equal to the number N_(SHADES)) at step 1220, the systemcontroller may determine at step 1224 a lowest optimal shade positionP_(LOW), for example, the lowest position of the optimal shade positionsP_(OPT)(t_(VAR)) determined at step 1218 for the motorized roller shadesof the group. At step 1226, the system controller may store the lowestoptimal shade position P_(LOW) in memory as the optimal shade groupposition P_(OPT-G)(t_(VAR)) at the variable time t_(VAR) (e.g., to beused in the timeclock event creation procedure 1020 of the timeclockconfiguration procedure 1000 shown in FIG. 15). If the variable timet_(VAR) is not equal to the end time t_(END) at step 1228, the systemcontroller may increment the variable time t_(VAR) by one interval(e.g., minute) at step 1230 and determine the optimal shade groupposition P_(OPT-G)(t_(VAR)) for the plurality of motorized roller shadesfor the next variable time t_(VAR) at step 1224. When the variable timet_(VAR) is equal to the end time t_(END) at step 1228, the optimal shadeposition procedure 1200 may exit.

FIG. 18 is a simplified flowchart of another example optimal shadeposition procedure 1300 that may be executed by a system controller todetermine optimal shade positions for a plurality of motorized windowtreatments (e.g., motorized roller shades) arranged along a non-linearfaçade (or multiple adjacent linear façades) of a building (e.g.,executed by the shade controller 920 of the load control system 900during the timeclock configuration procedure 1000 shown in FIG. 15). Thesystem controller may retrieve a start time t_(START) and an end timet_(END) of a timeclock schedule for the present day at step 1310 and mayset a variable time t_(VAR) equal to the start time t_(START) at step1312. The system controller may determine a representative façade angleφ_(F-REP) for the non-linear façade at step 1314 using, for example, thesolar azimuth angle φ_(S), the start façade angle φ_(START), and the endfaçade angle φ_(END). For example, the system controller may recalculatethe representative façade angle φ_(F-REP) at each interval (e.g.,minute) between the start time t_(START) and the end time t_(END) of thetimeclock schedule.

At step 1316, the system controller may determine the optimal shadeposition P_(OPT)(t_(VAR)) of the motorized roller shades that will limitthe sunlight penetration distance d_(PEN) in the space to a desiredmaximum sunlight penetration distance d_(MAX) at the variable timet_(VAR) and the representative façade angle φ_(F-REP). At step 1318, thesystem controller may store the optimal shade position P_(OPT)(t_(VAR))in memory as an optimal shade group position P_(OPT-G)(t_(VAR)) at thevariable time t_(VAR) (e.g., to be used in the timeclock event creationprocedure 1020 of the timeclock configuration procedure 1000 shown inFIG. 15). If the variable time t_(VAR) is not equal to the end timet_(END) at step 1320, the system controller may increment the variabletime t_(VAR) by, for example, one minute at step 1322 and determine theoptimal shade group position P_(OPT-G)(t_(VAR)) for the plurality ofmotorized roller shades for the next variable time t_(VAR) at step 1316.When the variable time t_(VAR) is equal to the end time t_(END) at step1320, the optimal shade position procedure 1300 may exit.

FIG. 19 is a simplified flowchart of an example representative façadeangle determination procedure 1400 that may be executed by a systemcontroller of a load control system to determine a representative façadeangle φ_(F-REP) for a plurality of motorized window treatments (e.g.,motorized roller shades) arranged along a non-linear façade (or multipleadjacent linear façades) of a building. For example, the representativefaçade angle determination procedure 1400 may be executed by the shadecontroller 920 of the load control system 900 at step 1314 of theoptimal shade position procedure 1300 shown in FIG. 18 to determine arepresentative façade angle φ_(F-REP) for a curved façade having a startfaçade angle φ_(START) and an end façade angle φ_(END). For example, theexample representative façade angle determination procedure 1400 may beexecuted for each interval (e.g., minute) between the start timet_(START) and the end time t_(END) of the timeclock schedule.

As shown in FIG. 19, the system controller may calculate the solarazimuth angle φ_(S) at step 1410 (e.g., using the variable time t_(VAR)from the optimal shade position procedure 1300). The system controllermay determine if the curved façade is facing north (e.g., if the curvedfaçade includes the façade angle of zero degrees) by determining the endfaçade angle φ_(END) and the start façade angle φ_(START) at step 1412(e.g., if φ_(START)<φ_(S)<360° or 0°<φ_(S)<φ_(END)). If the end façadeangle φ_(END) is less than the start façade angle φ_(START) at step 1412(e.g., the curved façade includes the façade angle of zero), the systemcontroller may determine if the solar azimuth angle φ_(S) is between thestart façade angle φ_(START) and the end façade angle φ_(END) bydetermining if the solar azimuth angle φ_(S) is between the start façadeangle φ_(START) and 360° at step 1414 or if the solar azimuth angleφ_(S) is between 0° and the end façade angle φ_(END) at step 1415. Ifthe solar azimuth angle φ_(S) is between the start façade angleφ_(START) and the end façade angle φ_(END) at steps 1414, 1415, thesystem controller may set the representative façade angle φ_(F-REP)equal to the solar azimuth angle φ_(S) at step 1416, and the façadeangle determination procedure 1400 may exit.

If the solar azimuth angle φ_(S) is not between the start and end façadeangles φ_(START), φ_(END) at steps 1414, 1415, the system controller maydetermine if the solar azimuth angle φ_(S) is closer to the start façadeangle φ_(START) or the end façade angle φ_(END) at step 1418. If thesolar azimuth angle φ_(S) is closer to the start façade angle φ_(START)(e.g., if |φ_(START)−φ_(S)|≦|φ_(START)−φ_(S)|) at step 1418, the systemcontroller may set the representative façade angle φ_(F-REP) equal tostart façade angle φ_(START) at step 1420, before the façade angledetermination procedure 1400 may exit. If the solar azimuth angle φ_(S)is closer to the end façade angle φ_(END) at step 1418, the systemcontroller may set the representative façade angle φ_(F-REP) equal toend façade angle φ_(END) at step 1422, and the façade angledetermination procedure 1400 may exit. The system controller may beconfigured to default to the start façade angle φ_(START) or the endfaçade angle φ_(END) when the solar azimuth angle φ_(S) is equidistantfrom each.

If the curved façade is not facing north at step 1412, the systemcontroller may determine if the solar azimuth angle φ_(S) is between thestart façade angle φ_(START) and the end façade angle φ_(END) (e.g., ifφ_(START)<φ_(S)<φ_(END)) at step 1424. If so, the system controller mayset the representative façade angle φ_(F-REP) equal to the solar azimuthangle φ_(S) at step 1426, and the façade angle determination procedure1400 may exit. If the solar azimuth angle φ_(S) is not between the startfaçade angle φ_(START) and the end façade angle φ_(END) at step 1424 andthe solar azimuth angle φ_(S) is closer to the start façade angleφ_(START) at step 1418, the system controller may set the representativefaçade angle φ_(F-REP) equal to start façade angle φ_(START) at step1420, before the façade angle determination procedure 1400 may exit. Ifthe solar azimuth angle φ_(S) is closer to the end façade angle φ_(END)at step 1418, the system controller may set the representative façadeangle φ_(F-REP) equal to end façade angle φ_(END) at step 1422, and thefaçade angle determination procedure 1400 may exit.

While north is characterized by a façade angle of zero degrees in thefaçade angle determination procedure 1400 of FIG. 19, another direction(e.g., south) may alternatively be assigned the façade angle of zerodegrees (e.g., based on user preference).

While the present disclosure has been described with reference to themotorized roller shades 140, 910, the concepts disclosed herein could beapplied to other types of motorized window treatments, such as motorizeddraperies, roman shades, Venetian blinds, tensioned roller shadesystems, and roller shade systems having pleated shade fabrics. Anexample of a motorized drapery system is described in greater detail incommonly-assigned U.S. Pat. No. 6,994,145, issued Feb. 7, 2006, entitledMOTORIZED DRAPERY PULL SYSTEM, the entire disclosure of which is herebyincorporated by reference. An example of a tensioned roller shade systemis described in greater detail in commonly-assigned U.S. Pat. No.8,056,601, issued Nov. 15, 2011, entitled SELF-CONTAINED TENSIONEDROLLER SHADE SYSTEM, the entire disclosure of which is herebyincorporated by reference. An example of a roller shade system having apleated shade fabric is described in greater detail in commonly-assignedU.S. Pat. No. 8,210,228, issued Jul. 3, 2012, entitled ROLLER SHADESYSTEM HAVING A HEMBAR FOR PLEATING A SHADE FABRIC, the entiredisclosure of which is hereby incorporated by reference.

Although features and elements are described herein in a particularcombination or order, each feature or element can be used alone or inany combination or order with the other features and elements. Themethods described herein may be implemented in a computer program,software, or firmware incorporated in a computer-readable medium forexecution by a computer or processor. Examples of computer-readablemedia include electronic signals (transmitted over wired or wirelessconnections) and computer-readable storage media. Examples ofcomputer-readable storage media include, but are not limited to, a readonly memory (ROM), a random access memory (RAM), removable disks, andoptical media such as CD-ROM disks, and digital versatile disks (DVDs).

What is claimed is:
 1. A load control system for controlling an amountof daylight entering a space of a building through at least one windowof a non-linear façade of the building, the non-linear façadecharacterized by at least two distinct façade angles, the load controlsystem comprising: at least two motorized window treatments locatedalong the non-linear façade for controlling the amount of daylightentering the space; and a system controller configured to transmitdigital commands to the motorized window treatments for controlling themotorized window treatments, the controller configured to: calculate anoptimal position for the motorized window treatments at each of aplurality of different times during a subsequent time interval using theat least two distinct façade angles, the optimal position calculated toprevent a sunlight penetration distance from exceeding a desired maximumsunlight penetration distance at each of the plurality of differenttimes during the time interval; use the optimal positions at theplurality of different times during the time interval to determine acontrolled position to which the at least two motorized windowtreatments will be controlled during the time interval; andautomatically adjust the position of each of the motorized windowtreatments to the controlled position at the beginning of the timeinterval so as to prevent the sunlight penetration distance fromexceeding the desired maximum sunlight penetration distance during thetime interval.